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(1) Field of the Invention
This invention relates to foam control agents for paints and coatings comprising a (a) a siloxane polyalkyleneoxide copolymer, (b) N,Nxe2x80x2-ethylene bisstearamide, and (c) a carrier.
(2) Description of the Related Art
A foam control agent is often essential to coatings, particularly latex emulsions. For purposes of describing this invention, xe2x80x9ccoatingsxe2x80x9d shall include xe2x80x9cpaintsxe2x80x9d. Without the foam control agent, bubbles will form in the coating. When the coating is applied to the substrate, the bubbles will dry on the substrate. These dried bubbles are not aesthetically pleasing. Furthermore, a substrate with dried bubbles is not effectively covered and protected from the environment.
There are many foam control agents for coatings currently available. Foam control agents typically consist of a hydrophobic material dispersed in a carrier, e.g. mineral oil, an alcohol, water, or other liquid. Typically, the hydrophobic material is a wax or silicone.
Typically, wax-based foam control agents are not as effective as silicone based products. Additionally, wax-based foam control agents tend to cause diminished specular gloss, which causes the coating to look duller than intended. On the other hand, silicone-based foam control agents are very effective at controlling foam, but often are difficult to incorporate into a coating. Surface defects, such as a xe2x80x9cripplexe2x80x9d, or xe2x80x9corange peel effectxe2x80x9d and xe2x80x9cpittingxe2x80x9d are typical defects seen with silicone-based foam control agents. Because of this, it is necessary to add of the xe2x80x9cdryxe2x80x9d components of the paint formulations with some liquid to make a slurry before the remaining xe2x80x9cwetxe2x80x9d components. The components, including the silicone defoamer, are then subjected to high agitation (xe2x80x9cgrind phasexe2x80x9d), which aids in the incorporation of a silicone defoamer.
The problem is that the xe2x80x9cgrind phasexe2x80x9d takes time, additional processing and additional energy to carry out. Therefore, there is an interest in reducing and/or eliminating the xe2x80x9cgrind phasexe2x80x9d without causing surface defects, such as a xe2x80x9cripplexe2x80x9d, or xe2x80x9corange peel effectxe2x80x9d and xe2x80x9cpittingxe2x80x9d.
All citations referred to under this description of the xe2x80x9cRelated Artxe2x80x9d and in the xe2x80x9cDetailed Description of the Inventionxe2x80x9d are expressly incorporated by reference.
The subject invention relates to foam control agents for paints and coatings comprising:
(a) a siloxane polyalkyleneoxide copolymer,
(b) N,Nxe2x80x2-ethylene bisstearamide, and
(c) a carrier.
The weight ratio of (a) to (b) is typically from 30:100 to 70:100, preferably from 50:100.
The use of these foam control agents is more effective as foam control agents than commercially available wax-based or silicone-base foam control agents. However, the gloss of coatings containing the foam control agents is equal to or better than the gloss of paints and coatings formulated with wax-based or silicone-base foam control agents. The invention eliminates these defects. The invention also relates to a method of formulating a coating, wherein the silicone-based foam control agent is added to the coating after the other solids and liquids are mixed without the requirement of xe2x80x9cgrind phasexe2x80x9d.
Not Applicable.
The detailed description and examples will illustrate specific embodiments of the invention will enable one skilled in the art to practice the invention, including the best mode. It is contemplated that many equivalent embodiments of the invention will be operable besides these specifically disclosed.
A broad range of water immiscible fluids can be used as the carrier. These include normally liquid hydrocarbons, polypropylene glycol, and vegetable oils. Preferably used are normally liquid hydrocarbons such as tetradecane, isooctane, hexadecane mineral oil, and kerosene. The hydrocarbon carrier generally has a pour point in the range of about xe2x88x9240xc2x0 C. to xe2x88x9210xc2x0C.
A variety of siloxanes can be used in the composition, including straight chain and branched silicones. For instance, linear polysiloxane having repeating internal siloxane moieties and an end blocked polypropylene oxide moiety, and those siloxanes described in U.S. Pat. No. 3,562,786 having a pendant polyoxyalkylene group containing both polyoxyethylene and polyoxypropylene moieties. Polysiloxanes containing pendant polyoxypropylene moieties bonded to a dimethylsiloxane moiety can also be used, for instance, see U.S. Pat. Nos. 5,558,806 and 5,534,609. However, the preferred siloxanes are siloxane polyalkyleneoxide copolymers represented by the following structural formula: 
where x is from about 50 to about 80, y is from about 7 to about 9, and n is from about 8 to 15, most preferably where x=about 65, y=about 8, and n=about 12.
Optional components of the foam control agent include sorbitan tristearate, waxes, surfactants, fatty acid esters, and end capped propylene oxide and/or butylene oxide polymers.
The amounts of the components used to make the foam control agent are as follows, where said weight percents are based upon the total weight of foam control agent:
(a) from 1 to 20 weight percent of a siloxane, preferably 1 to 10, more preferably 2 to 7 weight percent;
(b) from 1 to 15 weight percent of ethylene bis stearamide, preferably 1 to 10, more preferably 2 to 8 weight percent; and
(c) from 65 to 98 weight percent of a hydrocarbon carrier, preferably 75 to 95, more preferably 80 to 90 weight percent.
The foam control agents can be stored at temperatures of 0xc2x0 C. to 40xc2x0 C. for several months (typically up to six or even twelve months) before using them without a phase separation. They are typically mixed coatings (for purposes of describing this invention, xe2x80x9ccoatingxe2x80x9d includes xe2x80x9cpaintsxe2x80x9d), preferably latex emulsions, in amounts of 0.01 to 2.0 part by weight based upon the weight of the latex emulsion, preferably from 0.2 to 0.8 part by weight.
Such formulated paints and coatings may include one or more of the following components in a addition to a foam control agent: (1) 5.0 to 25.0 parts by weight of a latex emulsion (2) 20.0 to 60.0 parts by weight of water; (3) 1.0 to 40 parts by weight of a pigment; (4) 1.0 to 10.0 parts by weight of a polymeric binder; (5) 1.0 to 10 parts by weight of a coalescing aid; (6) 1.0 to 10.0 parts by weight of a thickener; (7) 0.1 to 2.0 parts by weight of a dispersant; (8) 0.01 to 1.0 part by weight of a biocide; (9) 5.0 to 40.0 parts by weight of an extender pigment; (10) 1.0 to 5.0 parts by weight of a rheology modifier; (11) 1.0 to 5.0 parts by weight of a glycol, e.g. propylene glycol; (12) 0.1 to 2.0 parts by weight of a surfactant; and (13) 0.01 to 2.0 parts by weight of a base, e.g. ammonium hydroxide.
The following abbreviations are used:
CARRIER paraffin oil having a viscosity of 100 SUS.
EBS Acrawax C-DF-1, ethylene bis stearamide, manufactured by Lonza.
POEOA polyoxyethylene ester of oleic acid having a polyoxethylene molecular weight of 600.
SC Silwet L-7510, manufactured by OSI, a silicone copolymer with polypropylene oxide, as shown in structural formula I.
SO silicone oil, manufactured by Dow Corning.
SS standard silica-based foam control agent, manufactured by Ashland Specialty Chemical, Drew Industrial Division.
SW standard wax-based foam control agent, manufactured by Ashland Specialty Chemical, Drew Industrial Division.
SSW standard silica-wax-based foam control agent, manufactured by Cognis Corporation.